Hard disk drives (HDD) are used in almost all computer system operations. In fact, most computing systems are not operational without some type of hard disk drive to store the most basic computing information such as the boot operation, the operating system, the applications, and the like. In general, the hard disk drive is a device which may or may not be removable, but without which the computing system will generally not operate.
The basic hard disk drive model includes a storage disk or hard disk that spins at a designed rotational speed. An actuator arm with a suspended slider is utilized to reach out over the disk. The slider is coupled with a suspension that supports both the body of the slider and a head assembly that has a magnetic read/write transducer or head or heads for reading/writing information to or from a location on the disk. The complete head assembly, e.g., the suspension, slider, and head, is called a head gimbal assembly (HGA).
The basic hard drive also typically includes a magnetic medium for storing data in magnetic form and the magnetic transducers are used to read and write magnetic data respectively off read and write tracks on the disks in the hard disk drive. A typical hard disk drive includes one or more disks which are mounted on a spindle motor. The spindle motor rotates the disks during read and write operations.
Information on the disks are typically stored in the form of magnetic transitions on a series of concentric spaced tracks, as shown in FIG. 1, formatted on the surface of the magnetic disks. The tracks are severally divided into a number of sectors with each sector comprising a number of information fields including fields for storing customer data, sector identification and synchronization information.
An actuator assembly typically including a number of arms with one or more transducers and sliders that fly over the surface of the disks as the rotation of the spindle motor increases causing the head to hover above the disk in an air bearing produced by the high speed disk rotation to read and write to and from the tracks.
In conventional hard disk drives, the data section include predefined customer data and a number of fields that store specific types of information that are both unique to the customer and to the drive. Such fields may include one or more synchronization fields, an error correction code (ECC) field, a cyclic redundancy code field (CRC), a seed randomizer field and a pad field. FIG. 2 illustrates a conventional data block that is written to each sector in the tracks. The data block shown in FIG. 2 is encoded for storage in the disk.
As shown in FIG. 2, each data block includes a preamble field 210, a block marker field 220, a randomizer seed field 220, a cyclical redundancy field 230, a data field 240, an error correction field 250 and a data pad 260. As shown in FIG. 2, each data block includes a preamble field, a block maker field, a randomizer seed, a data portion, a cyclical redundancy check (RC), a pad and an error correction field. The preamble bit sequence is selected to produce a read head response during a subsequent read process that is easy for the read channel to acquire phase lock with in preparation for decoding that data that follows. In the data block shown in FIG. 2, the randomizer seed is used to randomize the data portion and typically consists of a three byte sequence which is selected for each data field.
The pseudo random data sequence based randomizer is generally used to improve the reliability of the write and retrieval process. The randomizer is generally used to avoid worst-case data pattern sequence from being written or read to adjacent track thereby reducing interference between tracks. In the conventional data sector shown in FIG. 2, the randomizer seed is typically hard-coded with a fixed seed value in the randomizer field. To reduce the presence of errors in the customer data, the randomizer seed is typically hard-coded with a fixed seed.
Unfortunately hard-coding the seed code may result in the random data sequencer generating worst case data patterns to be written to sectors in the tracks. Thus, if a customer uses or prefers for some reason such a pattern, the drive may be initialized with a problematic randomizer seed.
In the conventional data block shown in FIG. 2, the assignment of the randomizer seed for each cylinder of the data tracks are hard-coded (fixed) thereby restricting the flexibility for a user to change the code in the event of errors or misreads. In addition to the above short comings, the conventional data sector lends itself to low signal to noise ratio between tracks and therefore often results in the wrong tracks written or read when a worst-case data pattern is initialized.
There is therefore a need for an improved data formatting approach which provides for efficient and flexible data decoding that allows for a dynamic allocation of randomizer seeds to reduce adjacent track interference and improve data integrity.